Method and device for determining elapsed sensor life

ABSTRACT

Methods and systems for determining elapsed sensor life in medical systems, and more specifically continuous analyte monitoring systems.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/195,449 filed Mar. 3, 2014, now U.S. Pat. No. 9,574,914,which is a continuation of U.S. patent application Ser. No. 12/495,219filed Jun. 30, 2009, now U.S. Pat. No. 8,665,091, which is acontinuation-in-part application of U.S. patent application Ser. No.12/117,681, filed May 8, 2008, now U.S. Pat. No. 8,461,985, entitled“Analyte Monitoring System and Methods,” which claims priority under 35U.S.C. § 119(e) to U.S. Provisional Application No. 60/916,744 filed May8, 2007, entitled “Analyte Monitoring System and Methods”, thedisclosures of each of which are incorporated herein by reference forall purposes.

BACKGROUND

The potential for severe complications caused by persistent high analytelevels and analyte fluctuations has provided the impetus to develop datamonitoring and management systems. In this regard, attempts have beenmade to detect and monitor certain analyte levels, e.g., glucose, withthe use of analyte monitoring systems designed to continuously orsemi-continuously monitor analyte data from a subject. The analytemonitoring systems often include a sensor configured to detect analytelevels and generate signals corresponding to the detected analytesignals. In some analyte monitoring systems, the sensor is inserted inthe body of the subject. Typically, such sensors have a sensor life ofabout a week. Thus, the sensor must be replaced periodically forcontinuous analyte detection and monitoring.

Occasionally, data monitoring systems undergo a fault condition, such asfor example a power loss, power shut-down, Watchdog reset, or variousother system or component failures. During these fault conditions, thesystem often loses data and time so there is no way for the system torecognize the amount of time elapsed during the fault condition. Thus,after fault conditions, it was necessary for the user to replace thesensor even if the fault condition occurred on day 2 of a 5-day or a7-day sensor. In addition to the financial costs of replacing a sensorthat had remaining life expectancy, the new sensor must be calibrated,requiring multiple finger sticks of the user and time. In view of theforegoing, it would be desirable to have a method and apparatus fordetermining the elapsed sensor life and/or remaining sensor lifesubsequent to a fault condition in a medical communication system, sothat the same sensor can be used after the fault condition.

SUMMARY

The purpose and advantages of the present invention will be set forth inand apparent from the description that follows, as well as will belearned by practice of the invention. Additional advantages of theinvention will be realized and attained by the methods and systemsparticularly pointed out in the written description and claims hereof,as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied herein and broadly described, theinvention includes devices and methods for analyte monitoring, forexample but not limited to, glucose monitoring. In accordance with oneaspect of the invention, a method is provided for operating an analytemonitoring system. The method includes providing a signal associatedwith initiation of an analyte sensor and providing a count from anincrementing counter. The method further includes storing a count thatis temporally associated with the signal associated with initiation ofthe analyte sensor. In one embodiment, initiation of the sensor andsignal occurs after placement of the sensor, e.g., transcutaneousimplantation or insertion of the sensor to a user. In this regard, thefirst count commensurate with sensor initiation is saved, for example,in a memory unit, such as a non-volatile memory. After the first countis stored, the counter continues to incrementally count. The incrementalcount can be based on a periodic cycle associated with calculation of ananalyte measurement by the analyte sensor. The periodic cycle can bebased on a time interval, e.g., every 30 or 60 seconds, and/or providedin data packets. The periodic calculations of analyte can be transmittedvia the data packets to a receiver or transceiver, as rolling data everyperiod.

In accordance with the invention, the method provides a way to determineelapsed (or remaining) sensor life for a particular sensor, for example,by a comparison between the stored first count and the incremental countbased on periodic cycles. Further, the elapsed time can be used torestart a sensor life timer and/or calibration timer, if desired.

In a further aspect of the invention, a second signal can be provided,wherein the second signal temporally associated with a second initiationof an analyte is stored, if a fault conditions occurs. In this regard,the elapsed time of the sensor can be determined by a comparison of thestored counts for the first and second signals that are temporallyassociated with initiation of the sensor and re-initiation of the sensorafter the occurrence of a fault condition. For example, but notlimitation, a system failure includes a battery drain, power shut-down(voluntary or involuntary), system reset.

In another aspect of the invention, the method includes providing asecond counter that incrementally counts each time a new sensor isinitialized. Thus, the method includes a first counter thatincrementally counts and a second counter that only incrementally countswhen a sensor is initialized. In this regard, the second counter canprovide information regarding how many sensors have been employed (orinitialized) in the data monitoring system.

In one embodiment, the second counter can be used in conjunction withthe first counter to determine the elapsed time for a particular sensor.In this regard, the incremental count of the first counter, such as aHobbs counter provides an indication of time duration, while the secondcounter, such as a sensor counter, can provide information regarding theoccurrence of sensor initiation. In this regard, the count of the Hobbscounter is saved when the sensor counter indicates initiation of asensor. Thus, the two counters, i.e., a comparison of informationderived from both the first counter and the second counter, can be usedto determine the elapsed time of an employed sensor.

In another aspect of the invention, a data processing device configuredto determine elapsed life of a sensor is provided. The data processingdevice includes a data processing section coupled to a datacommunication unit and at least one counter, e.g., Hobbs counter. Inaccordance with one aspect of the invention, the elapsed life of asensor is determined by comparing the stored count with the incrementedcount. In another embodiment, the data processing device includes twocounters, e.g., a Hobbs counter and a sensor counter. Elapsed life canbe determined by comparing the counts of both counters in conjunctionwith each other.

The data processing device can further include a storage unit such as anon-volatile memory unit to store the count. The non-volatile memoryunit can be disposed in a transmitter or a receiver unit. Further, thedata processing device can include an output unit for outputting amessage, such as date and time of sensor expiration, data and time fornext calibration, or a value derived from the count information, such asremaining life of the sensor. A method further includes displaying avalue derived or otherwise associated with the stored count, and/or theincremented count on a display unit. Further, the output unit can beconfigured to display an alarm when a calibration is needed, and/or whenthe sensor is close to expiration. The output unit includes one or moreof a visual, audible or tactile output. In accordance with oneembodiment, the display unit can be a receiver or, if desired, atransmitter. In one embodiment, the display is an OLED color display.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are intended toprovide further explanation of the invention claimed. The accompanyingdrawings are included to illustrate and provide a further understandingof the method and device of the invention. Together with thedescription, the drawings serve to explain the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a data monitoring and managementsystem for practicing one or more embodiments of the present invention;

FIG. 2 is a block diagram of the transmitter unit of the data monitoringand management system shown in FIG. 1 in accordance with one embodimentof the present invention;

FIG. 3 is a block diagram of the receiver/monitor unit of the datamonitoring and management system shown in FIG. 1 in accordance with oneembodiment of the present invention;

FIG. 4 is a flowchart illustrating data packet procedure includingrolling data for transmission in accordance with one embodiment of thepresent invention;

FIG. 5 is a flowchart illustrating data processing of the received datapacket including the rolling data in accordance with one embodiment ofthe present invention;

FIG. 6 is a block diagram illustrating the sensor and the transmitterunit of the data monitoring and management system of FIG. 1 inaccordance with one embodiment of the present invention;

FIG. 7 is a flowchart illustrating data communication using closeproximity commands in the data monitoring and management system of FIG.1 in accordance with one embodiment of the present invention;

FIG. 8 is a flowchart illustrating sensor insertion detection routine inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention;

FIG. 9 is a flowchart illustrating sensor removal detection routine inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention;

FIG. 10 is a flowchart illustrating the pairing or synchronizationroutine in the data monitoring and management system of FIG. 1 inaccordance with one embodiment of the present invention;

FIG. 11 is a flowchart illustrating the pairing or synchronizationroutine in the data monitoring and management system of FIG. 1 inaccordance with another embodiment of the present invention;

FIG. 12 is a flowchart illustrating the power supply determination inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention;

FIG. 13 is a flowchart illustrating close proximity command for RFcommunication control in the data monitoring and management system ofFIG. 1 in accordance with one embodiment of the present invention;

FIG. 14 is a flowchart illustrating analyte sensor identificationroutine in accordance with one embodiment of the present invention;

FIG. 15 is a flowchart illustrating the analyte sensor lifedetermination in accordance with one embodiment of the presentinvention; and

FIG. 16 is a flowchart illustrating the analyte sensor lifedetermination in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

As summarized above and as described in further detail below, inaccordance with various embodiments of the invention, there are provideda method and system for operating an analyte monitoring device.

FIG. 1 illustrates a data monitoring and management system such as, forexample, analyte (e.g., glucose) monitoring system 100 in accordancewith one embodiment of the present invention. The subject invention isfurther described primarily with respect to a glucose monitoring systemfor convenience and such description is in no way intended to limit thescope of the invention. It is to be understood that the analytemonitoring system may be configured to monitor a variety of analytes,e.g., lactate, and the like. Analytes that may be monitored include, forexample, acetyl choline, amylase, bilirubin, cholesterol, chorionicgonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA,fructosamine, glucose, glutamine, growth hormones, hormones, ketones,lactate, peroxide, prostate-specific antigen, prothrombin, RNA, thyroidstimulating hormone, and troponin. The concentration of drugs, such as,for example, antibiotics (e.g., gentamicin, vancomycin, and the like),digitoxin, digoxin, drugs of abuse, theophylline, and warfarin, may alsobe monitored. More than one analyte may be monitored by a single system,e.g. a single analyte sensor.

The analyte monitoring system 100 includes a sensor 101, a transmitterunit 102 coupleable to the sensor 101, and a primary receiver unit 104which is configured to communicate with the transmitter unit 102 via abi-directional communication link 103. The primary receiver unit 104 maybe further configured to transmit data to a data processing terminal 105for evaluating the data received by the primary receiver unit 104.Moreover, the data processing terminal 105 in one embodiment may beconfigured to receive data directly from the transmitter unit 102 via acommunication link which may optionally be configured for bi-directionalcommunication. Accordingly, transmitter unit 102 and/or receiver unit104 may include a transceiver.

Also shown in FIG. 1 is an optional secondary receiver unit 106 which isoperatively coupled to the communication link and configured to receivedata transmitted from the transmitter unit 102. Moreover, as shown inthe Figure, the secondary receiver unit 106 is configured to communicatewith the primary receiver unit 104 as well as the data processingterminal 105. Indeed, the secondary receiver unit 106 may be configuredfor bidirectional wireless communication with each or one of the primaryreceiver unit 104 and the data processing terminal 105. As discussed infurther detail below, in one embodiment of the present invention, thesecondary receiver unit 106 may be configured to include a limitednumber of functions and features as compared with the primary receiverunit 104. As such, the secondary receiver unit 106 may be configuredsubstantially in a smaller compact housing or embodied in a device suchas a wrist watch, pager, mobile phone, PDA, for example. Alternatively,the secondary receiver unit 106 may be configured with the same orsubstantially similar functionality as the primary receiver unit 104.The receiver unit may be configured to be used in conjunction with adocking cradle unit, for example for one or more of the following orother functions: placement by bedside, for re-charging, for datamanagement, for night time monitoring, and/or bidirectionalcommunication device.

In one aspect, sensor 101 may include two or more sensors, eachconfigured to communicate with transmitter unit 102. Furthermore, whileonly one transmitter unit 102, communication link 103, and dataprocessing terminal 105 are shown in the embodiment of the analytemonitoring system 100 illustrated in FIG. 1, it will be appreciated byone of ordinary skill in the art that the analyte monitoring system 100may include one or more sensors, multiple transmitter units 102,communication links 103, and data processing terminals 105. Moreover,within the scope of the present invention, the analyte monitoring system100 may be a continuous monitoring system, or semi-continuous, or adiscrete monitoring system. In a multi-component environment, eachdevice is configured to be uniquely identified by each of the otherdevices in the system so that communication conflict is readily resolvedbetween the various components within the analyte monitoring system 100.

In one embodiment of the present invention, the sensor 101 is physicallypositioned in or on the body of a user whose analyte level is beingmonitored. The sensor 101 may be configured to continuously sample theanalyte level of the user and convert the sampled analyte level into acorresponding data signal for transmission by the transmitter unit 102.In certain embodiments, the transmitter unit 102 may be physicallycoupled to the sensor 101 so that both devices are integrated in asingle housing and positioned on the user's body. The transmitter unit102 may perform data processing such as filtering and encoding on datasignals and/or other functions, each of which corresponds to a sampledanalyte level of the user, and in any event transmitter unit 102transmits analyte information to the primary receiver unit 104 via thecommunication link 103.

In one embodiment, the analyte monitoring system 100 is configured as aone-way RF communication path from the transmitter unit 102 to theprimary receiver unit 104. In such embodiment, the transmitter unit 102transmits the sampled data signals received from the sensor 101 withoutacknowledgement from the primary receiver unit 104 that the transmittedsampled data signals have been received. For example, the transmitterunit 102 may be configured to transmit the encoded sampled data signalsat a fixed rate (e.g., at one minute intervals) after the completion ofthe initial power on procedure. Likewise, the primary receiver unit 104may be configured to detect such transmitted encoded sampled datasignals at predetermined time intervals. Alternatively, the analytemonitoring system 100 may be configured with a bi-directional RF (orotherwise) communication between the transmitter unit 102 and theprimary receiver unit 104.

Additionally, in one aspect, the primary receiver unit 104 may includetwo sections. The first section is an analog interface section that isconfigured to communicate with the transmitter unit 102 via thecommunication link 103. In one embodiment, the analog interface sectionmay include an RF receiver and an antenna for receiving and amplifyingthe data signals from the transmitter unit 102, which are thereafter,demodulated with a local oscillator and filtered through a band-passfilter. The second section of the primary receiver unit 104 is a dataprocessing section which is configured to process the data signalsreceived from the transmitter unit 102 such as by performing datadecoding, error detection and correction, data clock generation, anddata bit recovery.

In operation, upon completing the power-on procedure, the primaryreceiver unit 104 is configured to detect the presence of thetransmitter unit 102 within its range based on, for example, thestrength of the detected data signals received from the transmitter unit102 and/or predetermined transmitter identification information. Uponsuccessful synchronization with the corresponding transmitter unit 102,the primary receiver unit 104 is configured to begin receiving from thetransmitter unit 102 data signals corresponding to the user's detectedanalyte level. More specifically, the primary receiver unit 104 in oneembodiment is configured to perform synchronized time hopping with thecorresponding synchronized transmitter unit 102 via the communicationlink 103 to obtain the user's detected analyte level.

Referring again to FIG. 1, the data processing terminal 105 may includea personal computer, a portable computer such as a laptop or a handhelddevice (e.g., personal digital assistants (PDAs)), and the like, each ofwhich may be configured for data communication with the receiver via awired or a wireless connection. Additionally, the data processingterminal 105 may further be connected to a data network (not shown) forstoring, retrieving and updating data corresponding to the detectedanalyte level of the user.

Within the scope of the present invention, the data processing terminal105 may include an infusion device such as an insulin infusion pump(external or implantable) or the like, which may be configured toadminister insulin to patients, and which may be configured tocommunicate with the receiver unit 104 for receiving, among others, themeasured analyte level. Alternatively, the receiver unit 104 may beconfigured to integrate or otherwise couple to an infusion devicetherein so that the receiver unit 104 is configured to administerinsulin therapy to patients, for example, for administering andmodifying basal profiles, as well as for determining appropriate bolusesfor administration based on, among others, the detected analyte levelsreceived from the transmitter unit 102.

Additionally, the transmitter unit 102, the primary receiver unit 104and the data processing terminal 105 may each be configured forbidirectional wireless communication such that each of the transmitterunit 102, the primary receiver unit 104 and the data processing terminal105 may be configured to communicate (that is, transmit data to andreceive data from) with each other via the wireless communication link103. More specifically, the data processing terminal 105 may in oneembodiment be configured to receive data directly from the transmitterunit 102 via a communication link, where the communication link, asdescribed above, may be configured for bi-directional communication.

In this embodiment, the data processing terminal 105 which may includean insulin pump, may be configured to receive the analyte signals fromthe transmitter unit 102, and thus, incorporate the functions of thereceiver unit 104 including data processing for managing the patient'sinsulin therapy and analyte monitoring. In one embodiment, thecommunication link 103 may include one or more of an RF communicationprotocol, an infrared communication protocol, a Bluetooth® enabledcommunication protocol, an 802.11x wireless communication protocol, oran equivalent wireless communication protocol which would allow secure,wireless communication of several units (for example, per HIPAArequirements) while avoiding potential data collision and interference.

FIG. 2 is a block diagram of the transmitter of the data monitoring anddetection system shown in FIG. 1 in accordance with one embodiment ofthe present invention. Referring to the Figure, the transmitter unit 102in one embodiment includes an analog interface 201 configured tocommunicate with the sensor 101 (FIG. 1), a user input 202, and atemperature detection section 203, each of which is operatively coupledto a transmitter processor 204 such as a central processing unit (CPU).As can be seen from FIG. 2, there are provided four contacts, three ofwhich are electrodes—work electrode (W) 210, guard contact (G) 211,reference electrode (R) 212, and counter electrode (C) 213, eachoperatively coupled to the analog interface 201 of the transmitter unit102 for connection to the sensor 101 (FIG. 1). In one embodiment, eachof the work electrode (W) 210, guard contact (G) 211, referenceelectrode (R) 212, and counter electrode (C) 213 may be made using aconductive material that is either printed or etched or ablated, forexample, such as carbon which may be printed, or a metal such as a metalfoil (e.g., gold) or the like, which may be etched or ablated orotherwise processed to provide one or more electrodes. Fewer or greaterelectrodes and/or contact may be provided in certain embodiments.

Further shown in FIG. 2 are a transmitter serial communication section205 and an RF transmitter 206, each of which is also operatively coupledto the transmitter processor 204. Moreover, a power supply 207 such as abattery is also provided in the transmitter unit 102 to provide thenecessary power for the transmitter unit 102.

Additionally, as can be seen from the Figure, clock 208 is provided to,among others, supply real time information to the transmitter processor204.

In one embodiment, a unidirectional input path is established from thesensor 101 (FIG. 1) and/or manufacturing and testing equipment to theanalog interface 201 of the transmitter unit 102, while a unidirectionaloutput is established from the output of the RF transmitter 206 of thetransmitter unit 102 for transmission to the primary receiver unit 104.In this manner, a data path is shown in FIG. 2 between theaforementioned unidirectional input and output via a dedicated link 209from the analog interface 201 to serial communication section 205,thereafter to the processor 204, and then to the RF transmitter 206. Assuch, in one embodiment, via the data path described above, thetransmitter unit 102 is configured to transmit to the primary receiverunit 104 (FIG. 1), via the communication link 103 (FIG. 1), processedand encoded data signals received from the sensor 101 (FIG. 1).Additionally, the unidirectional communication data path between theanalog interface 201 and the RF transmitter 206 discussed above allowsfor the configuration of the transmitter unit 102 for operation uponcompletion of the manufacturing process as well as for directcommunication for diagnostic and testing purposes.

As discussed above, the transmitter processor 204 is configured totransmit control signals to the various sections of the transmitter unit102 during the operation of the transmitter unit 102. In one embodiment,the transmitter processor 204 also includes a memory (not shown) forstoring data such as the identification information for the transmitterunit 102, as well as the data signals received from the sensor 101. Thestored information may be retrieved and processed for transmission tothe primary receiver unit 104 under the control of the transmitterprocessor 204. Furthermore, the power supply 207 may include acommercially available battery, which may be a rechargeable battery.

In certain embodiments, the transmitter unit 102 is also configured suchthat the power supply section 207 is capable of providing power to thetransmitter for a minimum of about three months of continuous operation,e.g., after having been stored for about eighteen months such as storedin a low-power (non-operating) mode. In one embodiment, this may beachieved by the transmitter processor 204 operating in low power modesin the non-operating state, for example, drawing no more thanapproximately 1 μA of current. Indeed, in one embodiment, a step duringthe manufacturing process of the transmitter unit 102 may place thetransmitter unit 102 in the lower power, non-operating state (i.e.,post-manufacture sleep mode). In this manner, the shelf life of thetransmitter unit 102 may be significantly improved. Moreover, as shownin FIG. 2, while the power supply unit 207 is shown as coupled to theprocessor 204, and as such, the processor 204 is configured to providecontrol of the power supply unit 207, it should be noted that within thescope of the present invention, the power supply unit 207 is configuredto provide the necessary power to each of the components of thetransmitter unit 102 shown in FIG. 2.

Referring back to FIG. 2, the power supply section 207 of thetransmitter unit 102 in one embodiment may include a rechargeablebattery unit that may be recharged by a separate power supply rechargingunit (for example, provided in the receiver unit 104) so that thetransmitter unit 102 may be powered for a longer period of usage time.Moreover, in one embodiment, the transmitter unit 102 may be configuredwithout a battery in the power supply section 207, in which case thetransmitter unit 102 may be configured to receive power from an externalpower supply source (for example, a battery) as discussed in furtherdetail below.

Referring yet again to FIG. 2, the temperature detection section 203 ofthe transmitter unit 102 is configured to monitor the temperature of theskin near the sensor insertion site. The temperature reading is used toadjust the analyte readings obtained from the analog interface 201. Incertain embodiments, the RF transmitter 206 of the transmitter unit 102may be configured for operation in the frequency band of approximately315 MHz to approximately 322 MHz, for example, in the United States. Incertain embodiments, the RF transmitter 206 of the transmitter unit 102may be configured for operation in the frequency band of approximately400 MHz to approximately 470 MHz. Further, in one embodiment, the RFtransmitter 206 is configured to modulate the carrier frequency byperforming Frequency Shift Keying and Manchester encoding. In oneembodiment, the data transmission rate is about 19,200 symbols persecond, with a minimum transmission range for communication with theprimary receiver unit 104.

Referring yet again to FIG. 2, also shown is a leak detection circuit214 coupled to the guard contact (G) 211 and the processor 204 in thetransmitter unit 102 of the data monitoring and management system 100.The leak detection circuit 214 in accordance with one embodiment of thepresent invention may be configured to detect leakage current in thesensor 101 to determine whether the measured sensor data are corrupt orwhether the measured data from the sensor 101 is accurate. Exemplaryanalyte systems that may be employed are described in, for example, U.S.Pat. Nos. 6,134,461, 6,175,752, 6,121,611, 6,560,471, 6,746,582, andelsewhere, the disclosure of each of which are incorporated by referencefor all purposes.

FIG. 3 is a block diagram of the receiver/monitor unit of the datamonitoring and management system shown in FIG. 1 in accordance with oneembodiment of the present invention. Referring to FIG. 3, the primaryreceiver unit 104 includes an analyte test strip, e.g., blood glucosetest strip, interface 301, an RF receiver 302, an input 303, atemperature detection section 304, and a clock 305, each of which isoperatively coupled to a receiver processor 307. As can be further seenfrom the Figure, the primary receiver unit 104 also includes a powersupply 306 operatively coupled to a power conversion and monitoringsection 308. Further, the power conversion and monitoring section 308 isalso coupled to the receiver processor 307. Moreover, also shown are areceiver serial communication section 309, and an output 310, eachoperatively coupled to the receiver processor 307.

In one embodiment, the test strip interface 301 includes a glucose leveltesting portion to receive a manual insertion of a glucose test strip,and thereby determine and display the glucose level of the test strip onthe output 310 of the primary receiver unit 104. This manual testing ofglucose may be used to calibrate the sensor 101 or otherwise. The RFreceiver 302 is configured to communicate, via the communication link103 (FIG. 1) with the RF transmitter 206 of the transmitter unit 102, toreceive encoded data signals from the transmitter unit 102 for, amongothers, signal mixing, demodulation, and other data processing. Theinput 303 of the primary receiver unit 104 is configured to allow theuser to enter information into the primary receiver unit 104 as needed.In one aspect, the input 303 may include one or more keys of a keypad, atouch-sensitive screen, or a voice-activated input command unit. Thetemperature detection section 304 is configured to provide temperatureinformation of the primary receiver unit 104 to the receiver processor307, while the clock 305 provides, among others, real time informationto the receiver processor 307.

Each of the various components of the primary receiver unit 104 shown inFIG. 3 is powered by the power supply 306 which, in one embodiment,includes a battery. Furthermore, the power conversion and monitoringsection 308 is configured to monitor the power usage by the variouscomponents in the primary receiver unit 104 for effective powermanagement and to alert the user, for example, in the event of powerusage which renders the primary receiver unit 104 in sub-optimaloperating conditions. An example of such sub-optimal operating conditionmay include, for example, operating the vibration output mode (asdiscussed below) for a period of time thus substantially draining thepower supply 306 while the processor 307 (thus, the primary receiverunit 104) is turned on. Moreover, the power conversion and monitoringsection 308 may additionally be configured to include a reverse polarityprotection circuit such as a field effect transistor (FET) configured asa battery activated switch.

The serial communication section 309 in the primary receiver unit 104 isconfigured to provide a bi-directional communication path from thetesting and/or manufacturing equipment for, among others,initialization, testing, and configuration of the primary receiver unit104. Serial communication section 309 can also be used to upload data toa computer, such as time-stamped blood glucose data. The communicationlink with an external device (not shown) can be made, for example, bycable, infrared (IR) or RF link. The output 310 of the primary receiverunit 104 is configured to provide, among others, a graphical userinterface (GUI) such as a liquid crystal display (LCD) for displayinginformation. Additionally, the output 310 may also include an integratedspeaker for outputting audible signals as well as to provide vibrationoutput as commonly found in handheld electronic devices, such as mobiletelephones presently available. In a further embodiment, the primaryreceiver unit 104 also includes an electro-luminescent lamp configuredto provide backlighting to the output 310 for output visual display indark ambient surroundings.

Referring back to FIG. 3, the primary receiver unit 104 in oneembodiment may also include a storage section such as a programmable,non-volatile memory device as part of the processor 307, or providedseparately in the primary receiver unit 104, operatively coupled to theprocessor 307. The processor 307 may be configured to synchronize with atransmitter, e.g., using Manchester decoding or the like, as well aserror detection and correction upon the encoded data signals receivedfrom the transmitter unit 102 via the communication link 103.

Additional description of the RF communication between the transmitterunit 102 and the primary receiver unit 104 (or with the secondaryreceiver unit 106) that may be employed in embodiments of the subjectinvention is disclosed in U.S. application Ser. No. 11/060,365 filedFeb. 16, 2005, now U.S. Pat. No. 8,771,183, entitled “Method and Systemfor Providing Data Communication in Continuous Glucose Monitoring andManagement System” the disclosure of which is incorporated herein byreference for all purposes.

Referring to the Figures, in one embodiment, the transmitter unit 102(FIG. 1) may be configured to generate data packets for periodictransmission to one or more of the receiver units 104, 106, where eachdata packet includes in one embodiment two categories of data—urgentdata and non-urgent data. For example, urgent data such as for exampleglucose data from the sensor and/or temperature data associated with thesensor may be packed in each data packet in addition to non-urgent data,where the non-urgent data is rolled or varied with each data packettransmission.

That is, the non-urgent data is transmitted at a timed interval so as tomaintain the integrity of the analyte monitoring system without beingtransmitted over the RF communication link with each data transmissionpacket from the transmitter unit 102. In this manner, the non-urgentdata, for example that are not time sensitive, may be periodicallytransmitted (and not with each data packet transmission) or broken upinto predetermined number of segments and sent or transmitted overmultiple packets, while the urgent data is transmitted substantially inits entirety with each data transmission.

Referring again to the Figures, upon receiving the data packets from thetransmitter unit 102, the one or more receiver units 104, 106 may beconfigured to parse the received data packet to separate the urgent datafrom the non-urgent data, and also, may be configured to store theurgent data and the non-urgent data, e.g., in a hierarchical manner. Inaccordance with the particular configuration of the data packet or thedata transmission protocol, more or less data may be transmitted as partof the urgent data, or the non-urgent rolling data. That is, within thescope of the present disclosure, the specific data packet implementationsuch as the number of bits per packet, and the like, may vary based on,among others, the communication protocol, data transmission time window,and so on.

In an exemplary embodiment, different types of data packets may beidentified accordingly. For example, identification in certain exemplaryembodiments may include—(1) single sensor, one minute of data, (2) twoor multiple sensors, (3) dual sensor, alternate one minute data, and (4)response packet. For single sensor one minute data packet, in oneembodiment, the transmitter unit 102 may be configured to generate thedata packet in the manner, or similar to the manner, shown in Table 1below.

TABLE 1 Single Sensor, One Minute of Data Number of Bits Data Field 8Transmit Time 14 Sensor 1 Current Data 14 Sensor 1 Historic Data 8Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8Rolling-Data-1

As shown in Table 1 above, the transmitter data packet in one embodimentmay include 8 bits of transmit time data, 14 bits of current sensordata, 14 bits of preceding sensor data, 8 bits of transmitter statusdata, 12 bits of auxiliary counter data, 12 bits of auxiliary thermistor1 data, 12 bits of auxiliary thermistor 1 data and 8 bits of rollingdata. In one embodiment of the present invention, the data packetgenerated by the transmitter for transmission over the RF communicationlink may include all or some of the data shown above in Table 1.

Referring back, the 14 bits of the current sensor data provides the realtime or current sensor data associated with the detected analyte level,while the 14 bits of the sensor historic or preceding sensor dataincludes the sensor data associated with the detected analyte level oneminute ago. In this manner, in the case where the receiver unit 104, 106drops or fails to successfully receive the data packet from thetransmitter unit 102 in the minute by minute transmission, the receiverunit 104, 106 may be able to capture the sensor data of a prior minutetransmission from a subsequent minute transmission.

Referring again to Table 1, the Auxiliary data in one embodiment mayinclude one or more of the patient's skin temperature data, atemperature gradient data, reference data, and counter electrodevoltage. The transmitter status field may include status data that isconfigured to indicate corrupt data for the current transmission (forexample, if shown as BAD status (as opposed to GOOD status whichindicates that the data in the current transmission is not corrupt)).Furthermore, the rolling data field is configured to include thenon-urgent data, and in one embodiment, may be associated with thetime-hop sequence number. In addition, the Transmitter Time field in oneembodiment includes a protocol value that is configured to start at zeroand is incremented by one with each data packet. In one aspect, thetransmitter time data may be used to synchronize the data transmissionwindow with the receiver unit 104, 106, and also, provide an index forthe Rolling data field.

In a further embodiment, the transmitter data packet may be configuredto provide or transmit analyte sensor data from two or more independentanalyte sensors. The sensors may relate to the same or different analyteor property. In such a case, the data packet from the transmitter unit102 may be configured to include 14 bits of the current sensor data fromboth sensors in the embodiment in which 2 sensors are employed. In thiscase, the data packet does not include the immediately preceding sensordata in the current data packet transmission. Instead, a second analytesensor data is transmitted with a first analyte sensor data.

TABLE 2 Dual Sensor Data Number of Bits Data Field 8 Transmit Time 14Sensor 1 Current Data 14 Sensor 2 Historic Data 8 Transmit Status 12 AUXCounter 12 AUX Thermistor 1 12 AUX Thermistor 2 8 Rolling-Data-1

In a further embodiment, the transmitter data packet may be alternatedwith each transmission between two analyte sensors, for example,alternating between the data packet shown in Table 3 and Table 4 below.

TABLE 3 Sensor Data Packet Alternate 1 Number of Bits Data Field 8Transmit Time 14 Sensor 1 Current Data 14 Sensor 1 Historic Data 8Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8Rolling-Data-1

TABLE 4 Sensor Data Packet Alternate 2 Number of Bits Data Field 8Transmit Time 14 Sensor 1 Current Data 14 Sensor 2 Historic Data 8Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8Rolling-Data-1

As shown above in reference to Tables 3 and 4, the minute by minute datapacket transmission from the transmitter unit 102 (FIG. 1) in oneembodiment may alternate between the data packet shown in Table 3 andthe data packet shown in Table 4. More specifically, the transmitterunit 102 may be configured in one embodiment to transmit the currentsensor data of the first sensor and the preceding sensor data of thefirst sensor (Table 3), as well as the rolling data, and further, at thesubsequent transmission, the transmitter unit 102 may be configured totransmit the current sensor data of the first and the second sensor inaddition to the rolling data (Table 4).

In one embodiment, the rolling data transmitted with each data packetmay include a sequence of various predetermined types of data that areconsidered not-urgent or not time sensitive. That is, in one embodiment,the following list of data shown in Table 5 may be sequentially includedin the 8 bits of transmitter data packet, and not transmitted with eachdata packet transmission of the transmitter (for example, with each 60second data transmission from the transmitter unit 102).

TABLE 5 Rolling Data Time Slot Bits Rolling Data 0 8 Mode 1 8 Glucose 1Slope 2 8 Glucose 2 Slope 3 8 Ref -R 4 8 Hobbs Counter, Ref-R 5 8 HobbsCounter 6 8 Hobbs Counter 7 8 Sensor Count

As can be seen from Table 5 above, in one embodiment, a sequence ofrolling data are appended or added to the transmitter data packet witheach data transmission time slot. In one embodiment, there may be 256time slots for data transmission by the transmitter unit 102 (FIG. 1),and where, each time slot is separated by approximately 60 secondinterval. For example, referring to the Table 5 above, the data packetin transmission time slot 0 (zero) may include operational mode data(Mode) as the rolling data that is appended to the transmitted datapacket. At the subsequent data transmission time slot (for example,approximately 60 seconds after the initial time slot (0)), thetransmitted data packet may include the analyte sensor 1 calibrationfactor information (Glucose 1 slope) as the rolling data. In thismanner, with each data transmission, the rolling data may be updatedover the 256 time slot cycle.

Referring again to Table 5, each rolling data field is described infurther detail for various embodiments. For example, the Mode data mayinclude information related to the different operating modes such as,but not limited to, the data packet type, the type of battery used,diagnostic routines, single sensor or multiple sensor input, or type ofdata transmission (RF communication link or other data link such asserial connection). Further, the Glucose 1-slope data may include an8-bit scaling factor or calibration data for first sensor (scalingfactor for sensor 1 data), while Glucose 2-slope data may include an8-bit scaling factor or calibration data for the second analyte sensor(in the embodiment including more than one analyte sensors).

In addition, the Ref-R data may include 12 bits of on-board referenceresistor used to calibrate the temperature measurement in the thermistorcircuit (where 8 bits are transmitted in time slot 3, and the remaining4 bits are transmitted in time slot 4), and the 20-bit Hobbs counterdata may be separately transmitted in three time slots (for example, intime slot 4, time slot 5 and time slot 6) to add up to 20 bits. In oneembodiment, the Hobbs counter may be configured to count each occurrenceof the data transmission (for example, a packet transmission atapproximately 60 second intervals) and may be incremented by a count ofone (1).

In one aspect, the Hobbs counter is stored in a nonvolatile memory ofthe transmitter unit 102 (FIG. 1) and may be used to ascertain the powersupply status information such as, for example, the estimated batterylife remaining in the transmitter unit 102. That is, with each sensorreplacement, the Hobbs counter is not reset, but rather, continues thecount with each replacement of the sensor 101 to establish contact withthe transmitter unit 102 such that, over an extended usage time periodof the transmitter unit 102, it may be possible to determine, based onthe Hobbs count information, the amount of consumed battery life in thetransmitter unit 102, and also, an estimated remaining life of thebattery in the transmitter unit 102.

That is, in one embodiment, the 20 bit Hobbs counter is incremented byone each time the transmitter unit 102 transmits a data packet (forexample, approximately each 60 seconds), and based on the countinformation in the Hobbs counter, in one aspect, the battery life of thetransmitter unit 102 may be estimated. In this manner, in configurationsof the transmitter unit 620 (see FIG. 6) where the power supply is not areplaceable component but rather, embedded within the housing thetransmitter unit 620, it is possible to estimate the remaining life ofthe embedded battery within the transmitter unit 620. Moreover, theHobbs counter is configured to remain persistent in the memory device ofthe transmitter unit 620 such that, even when the transmitter unit poweris turned off or powered down (for example, during the periodic sensorreplacement, RF transmission turned off period and the like), the Hobbscounter information is retained.

Referring to Table 5 above, the transmitted rolling data may alsoinclude 8 bits of sensor count information (for example, transmitted intime slot 7). The 8 bit sensor counter is incremented by one each time anew sensor is connected to the transmitter unit. The ASIC configurationof the transmitter unit (or a microprocessor based transmitterconfiguration or with discrete components) may be configured to store ina nonvolatile memory unit the sensor count information and transmit itto the primary receiver unit 104 (for example). In turn, the primaryreceiver unit 104 (and/or the secondary receiver unit 106) may beconfigured to determine whether it is receiving data from thetransmitter unit that is associated with the same sensor (based on thesensor count information), or from a new or replaced sensor (which willhave a sensor count incremented by one from the prior sensor count). Inthis manner, in one aspect, the receiver unit (primary or secondary) maybe configured to prevent reuse of the same sensor by the user based onverifying the sensor count information associated with the datatransmission received from the transmitter unit 102. In addition, in afurther aspect, user notification may be associated with one or more ofthese parameters. Further, the receiver unit (primary or secondary) maybe configured to detect when a new sensor has been inserted, and thusprevent erroneous application of one or more calibration parametersdetermined in conjunction with a prior sensor, that may potentiallyresult in false or inaccurate analyte level determination based on thesensor data.

FIG. 4 is a flowchart illustrating a data packet procedure includingrolling data for transmission in accordance with one embodiment of thepresent invention. Referring to FIG. 4, in one embodiment, a counter isinitialized (for example, to T=0) (410). Thereafter the associatedrolling data is retrieved from memory device, for example (420), andalso, the time sensitive or urgent data is retrieved (430). In oneembodiment, the retrieval of the rolling data (420) and the retrieval ofthe time sensitive data (430) may be retrieved at substantially the sametime.

Referring back to FIG. 4, with the rolling data and the time sensitivedata, for example, the data packet for transmission is generated (440),and upon transmission, the counter is incremented by one (450) and theroutine returns to retrieval of the rolling data (420). In this manner,in one embodiment, the urgent time sensitive data as well as thenon-urgent data may be incorporated in the same data packet andtransmitted by the transmitter unit 102 (FIG. 1) to a remote device suchas one or more of the receivers 104, 106. Furthermore, as discussedabove, the rolling data may be updated at a predetermined time intervalwhich is longer than the time interval for each data packet transmissionfrom the transmitter unit 102 (FIG. 1).

FIG. 5 is a flowchart illustrating data processing of the received datapacket including the rolling data in accordance with one embodiment ofthe present invention. Referring to FIG. 5, when the data packet isreceived (510) (for example, by one or more of the receivers 104, 106,in one embodiment), the received data packet is parsed so that theurgent data may be separated from the not-urgent data (stored in, forexample, the rolling data field in the data packet) (520). Thereafterthe parsed data is suitably stored in an appropriate memory or storagedevice (530).

In the manner described above, in accordance with one embodiment of thepresent invention, there is provided method and apparatus for separatingnon-urgent type data (for example, data associated with calibration)from urgent type data (for example, monitored analyte related data) tobe transmitted over the communication link to minimize the potentialburden or constraint on the available transmission time. Morespecifically, in one embodiment, non-urgent data may be separated fromdata that is required by the communication system to be transmittedimmediately, and transmitted over the communication link together whilemaintaining a minimum transmission time window. In one embodiment, thenon-urgent data may be parsed or broken up in to a number of datasegments, and transmitted over multiple data packets. The time sensitiveimmediate data (for example, the analyte sensor data, temperature data,etc.), may be transmitted over the communication link substantially inits entirety with each data packet or transmission.

FIG. 6 is a block diagram illustrating the sensor and the transmitterunit of the data monitoring and management system of FIG. 1 inaccordance with one embodiment of the present invention. Referring toFIG. 6, in one aspect, a transmitter unit 620 is provided in asubstantially water tight and sealed housing. The transmitter unit 620includes respective contacts (WRK, REF, CNTR, and GRD) for respectivelyestablishing electrical contact with one or more of the workingelectrode, the reference electrode, the counter electrode and the groundterminal (or guard trace) of the sensor 610. Also shown in FIG. 6 is aconductivity bar/trace 611 provided on the sensor 610. For example, inone embodiment, the conductivity bar/trace 611 may comprise a carbontrace on a substrate layer of the sensor 610. In this manner, in oneembodiment, when the sensor 610 is coupled to the transmitter unit 620,electrical contact is established, for example, via the conductivitybar/trace 611 between the contact pads or points of the transmitter unit620 (for example, at the counter electrode contact (CNTR) and the groundterminal contact (GRD) such that the transmitter unit 620 may be poweredfor data communication.

That is, during manufacturing of the transmitter unit 620, in oneaspect, the transmitter unit 620 is configured to include a power supplysuch as battery 621. Further, during the initial non-use period (e.g.,post manufacturing sleep mode), the transmitter unit 620 is configuredsuch that it is not used and thus drained by the components of thetransmitter unit 620. During the sleep mode, and prior to establishingelectrical contact with the sensor 610 via the conductivity bar/trace611, the transmitter unit 620 is provided with a low power signal from,for example, a low power voltage comparator 622, via an electronicswitch 623 to maintain the low power state of, for example, thetransmitter unit 620 components. Thereafter, upon connection with thesensor 610, and establishing electrical contact via the conductivitybar/trace 611, the embedded power supply 621 of the transmitter unit 620is activated or powered up so that some of all of the components of thetransmitter unit 620 are configured to receive the necessary powersignals for operations related to, for example, data communication,processing and/or storage.

In one aspect, since the transmitter unit 620 is configured to a sealedhousing without a separate replaceable battery compartment, in thismanner, the power supply of the battery 621 is preserved during the postmanufacturing sleep mode prior to use.

In a further aspect, the transmitter unit 620 may be disposed orpositioned on a separate on-body mounting unit that may include, forexample, an adhesive layer (on its bottom surface) to firmly retain themounting unit on the skin of the user, and which is configured toreceive or firmly position the transmitter unit 620 on the mounting unitduring use. In one aspect, the mounting unit may be configured to atleast partially retain the position of the sensor 610 in atranscutaneous manner so that at least a portion of the sensor is influid contact with the analyte of the user. Example embodiments of themounting or base unit and its cooperation or coupling with thetransmitter unit are provided, for example, in U.S. Pat. No. 6,175,752,incorporated herein by reference for all purposes.

In such a configuration, the power supply for the transmitter unit 620may be provided within the housing of the mounting unit such that, thetransmitter unit 620 may be configured to be powered on or activatedupon placement of the transmitter unit 620 on the mounting unit and inelectrical contact with the sensor 610. For example, the sensor 610 maybe provided pre-configured or integrated with the mounting unit and theinsertion device such that, the user may position the sensor 610 on theskin layer of the user using the insertion device coupled to themounting unit. Thereafter, upon transcutaneous positioning of the sensor610, the insertion device may be discarded or removed from the mountingunit, leaving behind the transcutaneously positioned sensor 610 and themounting unit on the skin surface of the user.

Thereafter, when the transmitter unit 620 is positioned on, over orwithin the mounting unit, the battery or power supply provided withinthe mounting unit is configured to electrically couple to thetransmitter unit 620 and/or the sensor 610.

Given that the sensor 610 and the mounting unit are provided asreplaceable components for replacement every 3, 5, 7 days or otherpredetermined time periods, the user is conveniently not burdened withverifying the status of the power supply providing power to thetransmitter unit 620 during use. That is, with the power supply orbattery replaced with each replacement of the sensor 610, a new powersupply or battery will be provided with the new mounting unit for usewith the transmitter unit 620.

Referring to FIG. 6 again, in one aspect, when the sensor 610 is removedfrom the transmitter unit 620 (or vice versa), the electrical contact isbroken and the conductivity bar/trace 611 returns to an open circuit. Inthis case, the transmitter unit 620 may be configured, to detect suchcondition and generate a last gasp transmission sent to the primaryreceiver unit 104 (and/or the secondary receiver unit 106) indicatingthat the sensor 610 is disconnected from the transmitter unit 620, andthat the transmitter unit 620 is entering a powered down (or low poweroff) state. And the transmitter unit 620 is powered down into the sleepmode since the connection to the power supply (that is embedded withinthe transmitter unit 620 housing) is broken.

In this manner, in one aspect, the processor 624 of the transmitter unit620 may be configured to generate the appropriate one or more data orsignals associated with the detection of sensor 610 disconnection fortransmission to the receiver unit 104 (FIG. 1), and also, to initiatethe power down procedure of the transmitter unit 620. In one aspect, thecomponents of the transmitter unit 620 may be configured to includeapplication specific integrated circuit (ASIC) design with one or morestate machines and one or more nonvolatile and/or volatile memory unitssuch as, for example, EEPROMs and the like.

Referring again to FIGS. 1 and 6, in one embodiment, the communicationbetween the transmitter unit 620 (or 102 of FIG. 1) and the primaryreceiver unit 104 (and/or the secondary receiver unit 106) may be basedon close proximity communication where bi-directional (oruni-directional) wireless communication is established when the devicesare physically located in close proximity to each other. That is, in oneembodiment, the transmitter unit 620 may be configured to receive veryshort range commands from the primary receiver unit 104 (FIG. 1) andperform one or more specific operations based on the received commandsfrom the receiver unit 104.

In one embodiment, to maintain secure communication between thetransmitter unit and the data receiver unit, the transmitter unit ASICmay be configured to generate a unique close proximity key at power onor initialization. In one aspect, the 4 or 8 bit key may be generatedbased on, for example, the transmitter unit identification information,and which may be used to prevent undesirable or unintendedcommunication. In a further aspect, the close proximity key may begenerated by the receiver unit based on, for example, the transmitteridentification information received by the transmitter unit during theinitial synchronization or pairing procedure of the transmitter and thereceiver units.

Referring again to FIGS. 1 and 6, in one embodiment, the transmitterunit ASIC configuration may include a 32 KHz oscillator and a counterwhich may be configured to drive the state machine in the transmitterunit ASIC. The transmitter ASIC configuration may include a plurality ofclose proximity communication commands including, for example, newsensor initiation, pairing with the receiver unit, and RF communicationcontrol, among others. For example, when a new sensor is positioned andcoupled to the transmitter unit so that the transmitter unit is poweredon, the transmitter unit is configured to detect or receive a commandfrom the receiver unit positioned in close proximity to the transmitterunit. For example, the receiver unit may be positioned within a coupleof inches of the on-body position of the transmitter unit, and when theuser activates or initiates a command associated with the new sensorinitiation from the receiver unit, the transmitter unit is configured toreceive the command from the receiver and, in its response data packet,transmit, among others, its identification information back to thereceiver unit.

In one embodiment, the initial sensor initiation command does notrequire the use of the close proximity key. However, other predefined orpreconfigured close-proximity commands may be configured to require theuse of the 8 bit key (or a key of a different number of bits). Forexample, in one embodiment, the receiver unit may be configured totransmit a RF on/off command to turn on/off the RF communication moduleor unit in the transmitter unit 102. Such RF on/off command in oneembodiment includes the close proximity key as part of the transmittedcommand for reception by the transmitter unit.

During the period that the RF communication module or unit is turned offbased on the received close proximity command, the transmitter unit doesnot transmit any data, including any glucose related data. In oneembodiment, the glucose related data from the sensor which are nottransmitted by the transmitter unit during the time period when the RFcommunication module or unit of the transmitter unit is turned off maybe stored in a memory or storage unit of the transmitter unit forsubsequent transmission to the receiver unit when the transmitter unitRF communication module or unit is turned back on based on the RF-oncommand from the receiver unit. In this manner, in one embodiment, thetransmitter unit may be powered down (temporarily, for example, duringair travel) without removing the transmitter unit from the on-bodyposition.

FIG. 7 is a flowchart illustrating data communication using closeproximity commands in the data monitoring and management system of FIG.1 in accordance with one embodiment of the present invention. Referringto FIG. 7, the primary receiver unit 104 (FIG. 1) in one aspect may beconfigured to retrieve or generate a close proximity command (710) fortransmission to the transmitter unit 102. To establish the transmissionrange (720), the primary receiver unit 104 may be positioned physicallyclose to (that is, within a predetermined distance from) the transmitterunit 102. For example, the transmission range for the close proximitycommunication may be established at approximately one foot distance orless between the transmitter unit 102 and the primary receiver unit 104.When the transmitter unit 102 and the primary receiver unit 104 arewithin the transmission range, the close proximity command, uponinitiation from the receiver unit 104 may be transmitted to thetransmitter unit 102 (730).

Referring back to FIG. 7, in response to the transmitted close proximitycommand, a response data packet or other responsive communication may bereceived (740). In one aspect, the response data packet or otherresponsive communication may include identification information of thetransmitter unit 102 transmitting the response data packer or otherresponse communication to the receiver unit 104. In one aspect, thereceiver unit 104 may be configured to generate a key (for example, an 8bit key or a key of a predetermined length) based on the transmitteridentification information (750), and which may be used in subsequentclose proximity communication between the transmitter unit 102 and thereceiver unit 104.

In one aspect, the data communication including the generated key mayallow the recipient of the data communication to recognize the sender ofthe data communication and confirm that the sender of the datacommunication is the intended data sending device, and thus, includingdata which is desired or anticipated by the recipient of the datacommunication. In this manner, in one embodiment, one or more closeproximity commands may be configured to include the generated key aspart of the transmitted data packet. Moreover, the generated key may bebased on the transmitter ID or other suitable unique information so thatthe receiver unit 104 may use such information for purposes ofgenerating the unique key for the bidirectional communication betweenthe devices.

While the description above includes generating the key based on thetransmitter unit 102 identification information, within the scope of thepresent disclosure, the key may be generated based on one or more otherinformation associated with the transmitter unit 102, and/or thereceiver unit combination. In a further embodiment, the key may beencrypted and stored in a memory unit or storage device in thetransmitter unit 102 for transmission to the receiver unit 104.

FIG. 8 is a flowchart illustrating sensor insertion detection routine inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention. Referring to FIG. 8, connectionto an analyte sensor is detected (810) based on, for example, a power upprocedure where the sensor conduction trace 611 (FIG. 6) is configuredto establish electrical contact with a predetermined one or more contactpoints on the transmitter unit 102. That is, when the sensor 101 (forexample, the electrodes of the sensor) is correspondingly connected tothe contact points on the transmitter unit 102, the transmitter unit 102is configured to close the circuit connecting its power supply (forexample, the battery 621 (FIG. 6)) to the components of the transmitterunit 102 and thereby exiting the power down or low power state intoactive or power up state.

In this manner, as discussed above, in one aspect, the transmitter unit102 may be configured to include a power supply such as a battery 621integrally provided within the sealed housing of the transmitter unit102. When the transmitter unit 102 is connected or coupled to therespective electrodes of the analyte sensor that is positioned in atranscutaneous manner under the skin layer of the patient, thetransmitter unit 102 is configured to wake up from its low power orsleep state (820), and power up the various components of thetransmitter unit 102. In the active state, the transmitter unit 102 maybe further configured to receive and process sensor signals receivedfrom the analyte sensor 101 (FIG. 1) (830), and thereafter, transmit theprocessed sensor signals (840) to, for example, the receiver unit 104(FIG. 1).

Accordingly, in one aspect, the sensor 610 (FIG. 6) may be provided witha conduction trace 611 which may be used to wake up or exit thetransmitter unit from its post manufacturing sleep mode into an activestate, by for example, establishing a closed circuit with the powersupply provided within the transmitter unit 102.

FIG. 9 is a flowchart illustrating sensor removal detection routine inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention. Referring to FIG. 9, when thesensor removal is detected (910) for example, based on detaching orremoving the transmitter unit 102 that was in contact with the sensor101, one or more status signal is generated (920), that includes, forexample, an indication that the sensor removal state has been detected,and/or an indication that the transmitter unit 102 will enter a sleepmode or a powered down status. Thereafter, the generated status signalin one aspect is transmitted, for example, to the receiver unit 104(930), and the transmitter unit 102 is configured to enter the powerdown mode or low power sleep mode (940).

In this manner, in one aspect, when the transmitter unit 102 isdisconnected from an active sensor 101, the transmitter unit 102 isconfigured to notify the receiver unit 104 that the sensor 101 has beendisconnected or otherwise, signals from the sensor 101 are no longerreceived by the transmitter unit 102. After transmitting the one or moresignals to notify the receiver unit 104, the transmitter unit 102 in oneembodiment is configured to enter sleep mode or low power state duringwhich no data related to the monitored analyte level is transmitted tothe receiver unit 104.

FIG. 10 is a flowchart illustrating the pairing or synchronizationroutine in the data monitoring and management system of FIG. 1 inaccordance with one embodiment of the present invention. Referring toFIG. 10, in one embodiment, the transmitter unit 102 may be configuredto receive a sensor initiate close proximity command (1010) from thereceiver unit 104 positioned within the close transmission range. Basedon the received sensor initiate command, the transmitter unitidentification information may be retrieved (for example, from anonvolatile memory) and transmitted (1020) to the receiver unit 104 orthe sender of the sensor initiate command.

Referring back to FIG. 10, a communication key optionally encrypted isreceived in one embodiment (1030), and thereafter, sensor related datais transmitted with the communication key on a periodic basis such as,every 60 seconds, five minutes, or any suitable predetermined timeintervals (1040).

Referring now to FIG. 11, a flowchart illustrating the pairing orsynchronization routine in the data monitoring and management system ofFIG. 1 in accordance with another embodiment of the present invention isshown. That is, in one aspect, FIG. 11 illustrates the pairing orsynchronization routine from the receiver unit 104. Referring back toFIG. 11, the sensor initiate command is transmitted to the transmitterunit 102 (1110) when the receiver unit 104 is positioned within a closetransmission range. Thereafter, in one aspect, the transmitteridentification information is received (1120) for example, from thetransmitter unit that received the sensor initiate command. Thereafter,a communication key (optionally encrypted) may be generated andtransmitted (1130) to the transmitter unit.

In the manner described above, in one embodiment, a simplified pairingor synchronization between the transmitter unit 102 and the receiverunit 104 may be established using, for example, close proximity commandsbetween the devices. As described above, in one aspect, upon pairing orsynchronization, the transmitter unit 102 may be configured toperiodically transmit analyte level information to the receiver unit 104for further processing.

FIG. 12 is a flowchart illustrating the power supply determination inthe data monitoring and management system of FIG. 1 in accordance withone embodiment of the present invention. That is, in one embodiment,using a counter, the receiver unit 104 may be configured to determinethe power supply level of the transmitter unit 102 battery so as todetermine a suitable time for replacement of the power supply or thetransmitter unit 102 itself. Referring to FIG. 12, periodic datatransmission is detected (1210), and a corresponding count in thecounter is incremented for example, by one with each detected datatransmission (1220). In particular, a Hobbs counter may be used in therolling data configuration described above to provide a count that isassociated with the transmitter unit data transmission occurrence.

Referring to FIG. 12, the updated or incremented count stored in theHobbs counter is periodically transmitted in the data packet (1230) fromthe transmitter unit 102 to the receiver unit 104. Moreover, theincremented or updated count may be stored (1240) in a persistentnonvolatile memory unit of the transmitter unit 102. Accordingly, basedon the number of data transmission occurrences, the battery power supplylevel may be estimated, and in turn, which may provide an indication asto when the battery (and thus the transmitter unit in the embodimentwhere the power supply is manufactured to be embedded within thetransmitter unit housing) needs to be replaced.

Moreover, in one aspect, the incremented count in the Hobbs counter isstored in a persistent nonvolatile memory such that, the counter is notreset or otherwise restarted with each sensor replacement.

FIG. 13 is a flowchart illustrating close proximity command for RFcommunication control in the data monitoring and management system ofFIG. 1 in accordance with one embodiment of the present invention.Referring to FIG. 13, a close proximity command associated withcommunication status, for example is received (1310). In one aspect, thecommand associated with the communication status may include, forexample, a communication module turn on or turn off command for, forexample, turning on or turning off the associated RF communicationdevice of the transmitter unit 102. Referring to FIG. 13, thecommunication status is determined (1320), and thereafter, modifiedbased on the received command (1330).

That is, in one aspect, using one or more close proximity commands, thereceiver unit 104 may be configured to control the RF communication ofthe transmitter unit 102 to, for example, disable or turn off the RFcommunication functionality for a predetermined time period. This may beparticularly useful when used in air travel or other locations such ashospital settings, where RF communication devices need to be disabled.In one aspect, the close proximity command may be used to either turn onor turn off the RF communication module of the transmitter unit 102,such that, when the receiver unit 104 is positioned in close proximityto the transmitter unit 102, and the RF command is transmitted, thetransmitter unit 102 is configured, in one embodiment, to either turnoff or turn on the RF communication capability of the transmitter unit102.

FIG. 14 is a flowchart illustrating analyte sensor identificationroutine in accordance with one embodiment of the present invention.Referring to FIG. 14, periodically, sensor counter information isreceived (1410), for example included as rolling data discussed above.The received sensor counter information may be stored in one or morestorage units such as a memory unit. When the sensor counter informationis received, a stored sensor counter information is retrieved (1420),and the retrieved sensor counter information is compared with thereceived sensor counter information (1430). Based on the comparisonbetween the retrieved sensor counter information and the received sensorcounter information, one or more signal is generated and output (1440).That is, in one aspect, the sensor counter in the transmitter unit 102may be configured to increment by one with each new sensor replacement.Thus, in one aspect, the sensor counter information may be associatedwith a particular sensor from which monitored analyte level informationis generated and transmitted to the receiver unit 104. Accordingly, inone embodiment, based on the sensor counter information, the receiverunit 104 may be configured to ensure that the analyte related data isgenerated and received from the correct analyte sensor transmitted fromthe transmitter unit 102. A method in one embodiment includes detectinga data transmission, incrementing a count associated with the detecteddata transmission, and storing the count. The count may be incrementedby one. In a further aspect, the method may include associating a powersupply level information with the stored count.

Moreover, the method may also include generating a signal associatedwith the stored count, and/or include outputting the generated signal,where outputting the generated signal may include one or more ofvisually displaying the generated signal, audibly outputting thegenerated signal, or vibratory outputting the generated signal.

In yet another aspect, the method may include transmitting the countwith the data transmission, where the count may be transmittedperiodically with the data transmission.

In still another aspect, the method may include associating a powersupply status with the count.

A data processing device in another embodiment may include a counter, adata communication unit, and a data processing section coupled to thedata communication unit and the counter, the data processing sectionconfigured to increment a count stored in the counter based on datatransmission by the data communication unit.

In one aspect, the counter may include a nonvolatile memory unit. Thecounter may include an EEPROM. The data communication unit may includean RF transceiver. The count stored in the counter may be incremented byone with each data transmission by the data communication unit.

The device may include a power supply coupled to the data processingunit, the data communication unit and the counter, where the countstored in the counter is not erased when the power supply is disabled orin low power state.

The data processing unit may be configured to estimate the power supplylife based on the stored count in the counter. The device in a furtheraspect may include an output section for outputting one or more signalsassociated with the count information, where the output section mayinclude one or more of a display unit, an audible output section, or avibratory output section.

In accordance with another aspect of the invention, elapsed sensor lifeand/or remaining sensor life is determinable. In this regard the sensorlife is tracked by a counter. Advantageously, after a system failuresuch as power shut-down, power loss, reset (e.g., Watchdog reset),battery drain, battery failure, the user of the data monitoring andmanagement system of FIG. 1 no longer needs to replace the sensor.Instead, the methods and system of the invention provide sensor lifeinformation to the user to enable the user to restart the analytemonitoring system using the same sensor, provided suitable remainingsensor life.

In one embodiment of the invention, as shown in FIG. 1, an analytemonitoring and management system includes an analyte sensor 101, atransmitter unit 102, a first counter (not shown), such as a Hobbscounter, and a receiver unit 104. The system can be configured todetermine the elapsed life (or remaining life) of an employed analytesensor 101. Advantageously, a user of the analyte monitoring system isnow able to determine a suitable time for replacement of the analytesensor, for example, in the event of a system failure during which thereceiver loses data information about calibration schedule and/or sensorexpiration schedule. Prior systems typically require the user to discardthe analyte sensor (regardless of remaining life available on thesensor) after the occurrence of a system failure due to the data loss oftime and day and calibration.

In accordance with one embodiment of the method, a signal associatedwith initiation of an analyte sensor is provided. For example, but notlimitation, upon initiation of the sensor 101 a signal is generatedwhich contains analyte measurement information. The signal can be atleast part of the data which forms a data packet that is encoded by thetransmitter unit 102 and/or transmitted via a communication link to areceiver unit 104. The receiver unit 104 can be configured to expectreceipt of a data packet at predetermined time intervals and/or atperiodic calculations of analyte. In one embodiment, the data packetsare transmitted by a transmitter unit 102 to receiver unit 104 everyminute. After the count temporally associated with initiation of thesensor is stored, the counter is configured to continually count byincrements. The increments can be for example, based on a periodiccycle, such as a measurement cycle. Alternatively, the increment can bebased on other factors, such as scheduled time interval. Additionally,the incremental count can be commensurate with the transmission of each(or a predetermined limited number) data packets and/or measurementcycles. Thus, for example, the measurement cycle can be a periodiccalculation of measured analyte (regardless of whether it istransmitted), or it can be based on a selected time interval, such asfor example 30 or 60 seconds, if desired. In some embodiments, the countinformation incrementally counted by the counter is transmitted to thereceiver unit 104 as part of the data packet. Further, the receiver isconfigured to extract the count from the data packet.

In one embodiment, the count information transmitted in the data packetupon sensor initiation is transmitted to receiver unit 104 where it isstored. Preferably, the count information is stored in nonvolatilememory such that it is not lost during a system failure. Preferably, thenonvolatile memory device is disposed in the receiver unit 104. However,transmitter unit 102 can be configured to store the count. The counterwhich can be part of the transmitter device 102, for example, is a Hobbscounter.

In accordance with one embodiment of the invention, elapsed life of ananalyte sensor (or remaining life expectancy of a sensor) can bedetermined by comparing the stored count which is based on sensorinitiation with an incremented count. As described above, theincremental count is based on a known measurement cycle, and/or timeinterval. Thus, the comparison of the count information can be used tocalculate the duration or elapsed time of the sensor use.

Further, the determined elapsed time can be used to restart operatingsystem timers, such as a sensor life timer and/or calibration timer.

FIG. 15 is a flowchart illustrating a method for determining elapsedlife of an analyte sensor employed in the analyte monitoring andmanagement system of FIG. 1. As depicted and embodied herein, an analytesensor is initiated (1510) to detect and/or measure the presence of ananalyte in a bodily fluid. For the purpose of illustration, but notlimitation, the analyte can be glucose and the bodily fluid can beblood, plasma or interstitial fluid. However, other analytes can bemonitored, such as but not limited to lactate. A counter, such as forexample a Hobbs counter described above, is configured to incrementallycount. The Hobbs counter may be disposed for example in the transmitterof the analyte monitoring system. The count or value that is temporallyassociated with the initiation of the sensor (1520) (or a signalgenerated by the sensor during initiation) is stored in a memory unit(count 1) (1530). In addition to the storage of the first count, thecounter continues to incrementally count. As described, the incrementalcount can be based on a known measurement cycle, such as that of theanalyte sensor detecting levels of an analyte in the bodily fluid.Alternatively, the incremental count can be based on a time interval. Inthe event that a system failure occurs, the counter is configured tostore a second count temporally associated with re-initiation of theanalyte sensor (count 2) (1540). In this regard, the elapsed time orduration of use of the analyte sensor prior to the fault condition canbe determined by comparing count 2 and count 1 (1550). Thus, providedthat at least some life expectancy of the analyte sensor remains, theuser may continue to use the analyte sensor, rather than being requiredto change the sensor with a replacement sensor because all data waslost. In the event that no or less than a predetermined amount of liferemains on the analyte sensor, the monitoring system can be configuredto display a message or alarm that the sensor expired or is soon toexpire (1560). In a further embodiment, the determined elapsed time canbe used to restart a sensor life timer and/or calibration timer (1570).

The term system failure as used herein means a fault condition such asany condition by which the analyte monitoring system loses power. Somenon-limiting examples of fault conditions include a reset (e.g.,receiver reset), battery drain, battery replacement, power loss, powershut-down, or a fatal error. Typically, after such fault conditions,analyte monitoring systems prompt the user to replace the sensor becauseinformation about the life of the sensor was lost at the time of thefault condition. This aspect of the invention, allows the use of thesame sensor after a fault condition occurs (provided that the sensorlife has not expired), thereby saving the user costs associated withusing a new sensor and the hardship of undergoing another calibrationschedule.

In another embodiment of the invention, the analyte monitoring andmanagement system includes a first counter to incrementally count basedon a time interval, or calculation of an analyte, and a second counterto incrementally count by one only if a new sensor is initiated. In thisregard, the incremental count of the second sensor can indicate how manyor which sensor is being employed. For example, if the second counterhas an incremental count of one, then the first sensor is beingemployed, if the second counter has an incremental count of 2, then thesecond sensor is being employed. Thus, the second counter can track howmany sensors have been employed. In a further aspect of the invention,if the receiver connects to the transmitter and in response the receiverreceives a count change compared to the sensor count before the systemfailure, the receiver acknowledges that a different sensor was implantedor otherwise employed during the receiver shut down. In this regard, theprevious sensor life time is terminated, and a new count begins for thenew sensor. Additionally, when the second counter increments by onebecause a new sensor is used then the count of the first counter isstored.

Referring to another embodiment of the invention, as described in FIG.16, the first counter can be a Hobbs counter which is initiated (forexample, to T=0) (1610). Thereafter the Hobbs counter incrementallycounts (for example, to T=T+1) (1620). The second counter can be forexample a sensor counter that is configured to count incrementally withthe initiation of each new analyte sensor (for example, S=S+1) (1640).Thus, if there is no new sensor employed, the count of the secondcounter does not increment (1630). Further, a count of the Hobbs counter(1650) (which is commensurate with an incremental count of the sensorcounter) is stored (1660). Thus, the system contains stored dataregarding the data and time of each new sensor initiation. Accordingly,the first and second counters in conjunction can be used to determineelapsed life of the analyte sensor. As shown in FIG. 16, if the sensorlife is less than the sensor life expectancy (1670), then the cycle isrepeated. If the sensor life is expired or close to its expiration, thenan alarm or message can be output (1680).

In one embodiment, the first counter is a 20-bit counter, and the secondcounter is an 8-bit counter. However, other types of counters can beutilized.

In another aspect of the invention, an output unit is provided. Theoutput unit can be configured to display a value derived from the countinformation. In this regard, the output unit can be a display device.The display device can be an Organic Light Emitting Diode (OLED) displaydevice, for example, a small molecule or polymer OLED. The OLED displaydevice can provide wide viewing angles, high brightness, colors, andcontrast levels.

It will be apparent to those skilled in the art that variousmodifications and alterations in the methods and systems of thisinvention will be apparent to those skilled in the art without departingfrom the scope and spirit of the invention. Although the invention hasbeen described in connection with specific embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. It is intended that the following claimsdefine the scope of the present invention and that structures andmethods within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A method, comprising: providing an analyte sensorto measure an analyte level; and operating sensor electronicsoperatively coupled to the analyte sensor, by: incrementing a firstcount based on a time interval; and incrementing a second count onlywhen a new analyte sensor is initiated.
 2. The method of claim 1,further comprising determining how many sensors have been initiatedbased on the second count.
 3. The method of claim 1, further comprisingoperating the sensor electronics to communicate with a receiving device.4. The method of claim 3, further comprising incrementing a third counteach time the sensor electronics communicates with the receiving device.5. The method of claim 4, further comprising operating the sensorelectronics to communicate the second count to the receiving device. 6.The method of claim 5, further comprising determining whether an analytesensor life is expired based on the communicated second count, andproviding an alarm when the analyte sensor life is determined to beexpired.
 7. The method of claim 1, further comprising operating thesensor electronics to store data for the first count in a memory whenthe second count is incremented.
 8. The method of claim 1, wherein thetime interval is a periodic scheduled time interval.
 9. The method ofclaim 1, wherein the analyte sensor comprises a plurality of electrodesincluding a working electrode comprising an analyte-responsive enzymebonded to a polymer disposed on the working electrode.
 10. The method ofclaim 9, wherein the working electrode comprises a mediator crosslinkedwith the polymer disposed on the working electrode.
 11. The method ofclaim 1, wherein the analyte sensor comprises a plurality of electrodesincluding a working electrode comprising a mediator bonded to a polymerdisposed on the working electrode.
 12. The method of claim 1, whereinthe analyte sensor is a glucose sensor.
 13. The method of claim 1,further comprising using the first count and the second count toestimate a battery life of the sensor electronics.
 14. The method ofclaim 1, further comprising turning off the sensor electronics, andmaintaining data corresponding to the first count and the second countin a memory of the sensor electronics when the sensor electronics areturned off.
 15. The method of claim 1, further comprising storing datafor each new sensor initiation of each sensor operatively coupled to thesensor electronics.
 16. The method of claim 1, further comprisingstoring a 20-bit counter corresponding to the first count and an 8-bitcounter for the second count in a memory of the sensor electronics. 17.The method of claim 16, further comprising initiating the new analytesensor when at least a portion of the new analyte sensor is positionedin fluid contact with bodily fluid under a skin surface.
 18. The methodof claim 17, wherein initiating the new analyte sensor further comprisesreceiving a signal associated with the new analyte sensor.
 19. Themethod of claim 18, wherein the signal associated with the new analytesensor contains analyte level information.
 20. The method of claim 1,further comprising providing an output unit for outputting a messageincluding a value derived from at least one of the first count or thesecond count.